(1) Field of the Invention
This invention relates to a flexible ferrite loaded loop antenna assembly and more particularly, to a flexible antenna assembly that will permit VLF/LF reception in the athwart direction (side to side) relative to its deployment along a cable.
(2) Description of the Prior Art
Three types of antennas have been used by submarines for reception of radio signals in the very low frequency and low frequency (VLF/LF) transmission bands. The first is a mast mounted antenna which is omni-directional and extends above the ocean surface. Such an antenna is used when the submarine is not concerned with being detected. The second, a voltage probe antenna exists in the periscope and extends above the ocean surface. The third, a buoyant cable antenna, is used when the submarine is submerged and must avoid detection.
The buoyant cable antenna floats on the ocean surface and is deployed along with a buoyant cable. The buoyant cable antenna must be flexible because it is launched through a transfer mechanism which bends the cable through a six inch radius. Because flexibility is required, buoyant cable antennas have employed a horizontal wire antenna element which can receive only in the fore and aft (front and back) direction relative to its deployment. This limits the reception capability of the buoyant cable antenna.
Accordingly, there is a need for a buoyant cable antenna system with omni-directional capability that can be launched under all sea conditions at depth without danger of being detected. To achieve omni-directionality, such a buoyant cable antenna system requires the addition of a loop antenna that can receive VLF/LF in athwart direction relative to ship's heading. A buoyant cable mounted loop antenna must be capable of being bent through at least a six inch radius during deployment, and pass signals received on the wire antenna. Therefore, what is required is a buoyant cable antenna system including a flexible loop antenna which will provide the desired omni-directional signal reception and is compatible with existing deployment mechanisms.